Study of the mechanism of the antioxidant action of ethoxyquin

Taimr, L.

doi:10.1002/apmc.1994.052170112

Cited by 9 publications

(3 citation statements)

References 9 publications

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“…Ethoxyquin acts primarily as a hydrogen atom donor toward peroxyl radicals. The major oxidation products of ethoxyquin − result from heterodimerization (compound 2 ) or loss of methyl (quinoline 3 ) or ethyl (quinoline quinone imine 4 ) radicals from the corresponding aminyl radical. The hyperfine splittings recorded in the EPR spectrum of the aminyl radical are indicative of extensive delocalization of the unpaired electron …”

Section: Introductionmentioning

confidence: 99%

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

et al. 2007

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6-(Ethylthio)-, 6-(ethylseleno)-, and 6-(ethyltelluro)-2,2,4-trimethyl-1,2-dihydroquinoline-three heavier chalcogen analogues of ethoxyquin-were prepared by dilithiation of the corresponding 6-bromodihydroquinoline followed either by treatment with the corresponding diethyl dichalcogenide (sulfur derivative) or by insertion of selenium/tellurium into the carbon-lithium bond, oxidation to a diaryl dichalcogenide, borohydride reduction, and finally alkylation of the resulting areneselenolate/arenetellurolate. Ethoxyquin, its heavier chalcogen analogues, and the corresponding 6-PhS, 6-PhSe, and 6-PhTe derivatives were assayed for both their chain-breaking antioxidative capacity and their ability to catalyze reduction of hydrogen peroxide in the presence of a stoichiometric amount of a thiol reducing agent (thiol peroxidase activity). Ethoxyquin itself turned out to be the best inhibitor of azo-initiated peroxidation of linoleic acid in a water/chlorobenzene two-phase system. In the absence of N-acetylcysteine as a coantioxidant in the aqueous phase, it inhibited peroxidation as efficiently as alpha-tocopherol but with a more than 2-fold longer inhibition time. In the presence of 0.25 mM coantioxidant in the aqueous phase, the inhibition time was further increased by almost a factor of 2. This is probably due to thiol-mediated regeneration of the active antioxidant across the lipid-aqueous interphase. The ethyltelluro analogue 1d of ethoxyquin was a similarly efficient quencher of peroxyl radicals compared to the parent in the two-phase system, but less regenerable. Ethoxyquin was found to inhibit azo-initiated oxidation of styrene in the homogeneous phase (chlorobenzene) almost as efficiently (kinh = (2.0 +/- 0.2) x 106 M-1 s-1) as alpha-tocopherol with a stoichiometric factor n = 2.2 +/- 0.1. At the end of the inhibition period, autoxidation was additionally retarded, probably by ethoxyquin nitroxide formed during the course of peroxidation. The N-H bond dissociation enthalpy of ethoxyquin (81.3 +/- 0.3 kcal/mol) was determined by a radical equilibration method using 2,6-dimethoxyphenol and 2,6-di-tert-butyl-4-methylphenol as equilibration partners. Among the investigated compounds, only the tellurium analogues 1d and, less efficiently, 1g had a capacity to catalyze reduction of hydrogen peroxide in the presence of thiophenol. Therefore, analogue 1d is the only antioxidant which is multifunctional (chain-breaking and preventive) in character and which can act in a truly catalytic fashion to decompose both peroxyl radicals and organic hydroperoxides in the presence of suitable thiol reducing agents.

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Section: Introductionmentioning

confidence: 99%

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

et al. 2007

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“…It was reported that PBN inhibits both synthesis of nitric oxide (NO) and formation of NO-mediated 3-nitrotyrosine adducts in activated astrocytes. Quinoline compounds have numerous biological applications such as anti-malarial [14], anti-microbial [15], anti-inflammatory [16], anti-cancer [17], anti-ulcer [18], antioxidant [19], and antiviral [20] activities.…”

Section: Introductionmentioning

confidence: 99%

C‐(2‐Chloroquinoline‐3‐yl)‐N‐phenyl Nitrone: New Synthetic Antioxidant Inhibits Proliferation and Induces Apoptosis of Breast Carcinoma MCF‐7 Cells

Ramadan

Gamal‐Eldeen²,

Abdel‐Aziz

et al. 2006

Archiv der Pharmazie

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In this work, a new quinoline nitrone derivative, C-(2-chloroquinoline-3-yl)-N-phenyl nitrone (CQPN) was successfully prepared and proved by spectral analysis. The antioxidant activity of CQPN against various radicals was investigated and its anti-cancer properties against different human tumor cell lines including the solid tumor cell lines hepatocarcinoma (Hep-G2) and breast carcinoma (MCF-7); the hematopoietic tumor cell line lymphoblastic leukemia (1301) was also explored. CQPN activities were compared to that of the known nitrone C-phenyl-N-tert-butyl nitrone (PBN). Our results showed that although PBN was the stronger antioxidant than CQPN, the latter was an effective scavenger of different non-physiological (1,1-diphenyl-2-picrylhyrazyl) and physiological (peroxyl and hydroxyl) radicals. Both of CQPN and PBN possess a significant inhibitory property against LPS-stimulated NO production in macrophage. CQPN and PBN treatment resulted in a growth inhibition in Hep-G2 cells (IC50 31.42 microM and 18.6 microM, respectively). Unlike PBN, CQPN strongly inhibited the growth of MCF-7 cells (IC50 14.01 microM) in a dose-dependent manner. On contrary, CQPN and PBN exhibited a proliferative stimulatory activity of the immune cells including macrophages and lymphocytes. Exploring the cytotoxic effect of CQPN against MCF-7 cells indicated that CQPN led to a major time-dependent disturbance in the cell-cycle phases including progressive arrest in both S- and G2/M-phases. This disturbance was found to be associated with a kinetic induction of apoptosis. The novel nitrone derivative CQPN is a strong antioxidant, though less than PBN, and it may be an effective anti-proliferative compound against breast carcinoma.

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“…Animal feeds often utilize ethoxyquin as it is the most effective antioxidant . This exceptional effectiveness is contributed to the ability for the oxidization products of ethoxyquin to also contain antioxidant properties (Taimr, 1994). Furthermore, the half-life of these products, such as ethoxyquin dimer, are considerably longer than ethoxyquin .…”

Section: Antioxidantsmentioning

confidence: 99%

Investigations of the oxidative stability of rendered protein meals and their suitability as feed ingredients

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Study of the mechanism of the antioxidant action of ethoxyquin

Cited by 9 publications

References 9 publications

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

Antioxidant Profile of Ethoxyquin and Some of Its S, Se, and Te Analogues

C‐(2‐Chloroquinoline‐3‐yl)‐N‐phenyl Nitrone: New Synthetic Antioxidant Inhibits Proliferation and Induces Apoptosis of Breast Carcinoma MCF‐7 Cells

Investigations of the oxidative stability of rendered protein meals and their suitability as feed ingredients

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